IX. Translate from Russian into English.

1. Гидротермальные растворы часто осаждаются в разломах, формируя богатые рудные жилы.

2. Добавление магмы, нагревание и складчатость действуют вместе и утолщают континентальную кору и литосферу.

3. Нормальные сбросы и грабены распространены в центрах спрединга.

Text XV unit XV plate tectonics. A first look

I. Give Russian equivalents.

To break into segments; hard rock; at certain depth; the thinnest layer; plate boundary; to meet and interact; to move apart; separating plates; to drift horizontally; to slide past each other; to sink into the mantle; relative to one another.

II. Give English equivalents.

В противоположном направлении; дивергентная плитная граница; конвергентная плитная граница; трансформная плитная граница; рифтовая долина; тектонические плиты; самый верхний (внешний) слой; менять как скорость, так и направление.

III. Match the words from “a” and “b” to make word combinations.

1. to consist of; average thickness of; throughout; to vary; the upper part; at a rate of; to compress the inner core; to have similar; to be located; to be packed;

2. of the mantle; continental crust; chemical composition; hard strong rock; the mantle; tightly together; with depth; to a solid; a few centimeters per year; at continental margins.

IV. Complete the sentences.

1. . . . . is a long, narrow belt where a lithospheric plate is sinking into the mantle.

2. . . . . is the process when two plates converge, the dense plate dives beneath the lighter one and sinks into the mantle.

3. A divergent plate boundary can rip a continent in half in a process called . . . .

4. The lithosphere is broken into seven large segments called . . . .

5. . . . . lies directly below the crust.

(tectonic plates; subduction; continental rifting; subduction zone; mantle)

V. Choose the right word.

1. Scientists . . . . the Earth as a layered planet. (descriptive; description; describe)

2. The average . . . . of continental crust is about 20 to 40 kilometers. (thickness; thick; thicken)

3. These changes create . . . . with the mantle. (layer; layering; layered)

4. The core is composed . . . . of iron and nickel. (large; largest; largely)

5. . . . . plates can move relative to one another in three different ways. (neighbouring; neighbourhood; neighbour)

VI. Translate the sentences.

1. Geologists know the method to be chosen in any particular case to depend on the thickness of overburden and the surface relief.

2. Scientist consider sunlight to be a promising source of energy.

3. Volcanologists know some volcanoes to explode violently or gently.

4. Latest studies show mountain ranges to originate at divergent plate boundaries on land.

VII. Make up questions.

1. Geologists study the Earth and its interior. (What?)

2. Sea life concentrates near the ocean surface. (Where?)

3. Atmosphere is composed of various gases. (General question)

VIII. Read the text.

About 1 million earthquakes shake the Earth each year; most are so weak that we do not feel them, but the strongest demolish cities and kill thousands of people. Most of us have seen televised coverage of volcanic eruptions blasting molten rock and ash into the sky, destroying villages and threatening cities. Over geologic time, mountain ranges rise and then erode away, continents migrate around the globe, and ocean basins open and close.

Before 1960, no single theory explained all of these manifestations of the active Earth. In the early 1960s, geologists developed the plate tectonics theory, which provides a single, unifying framework that explains earthquakes, volcanic eruptions, mountain building, moving continents, and many other geologic events. It also allows geologists to identify many geologic hazards before they affect humans.

Are the following statements true or false?

1. Earthquakes are so rare at the Earth’s surface that we don’t know much about them.

2. Earthquakes cause mountain ranges to rise, continents to migrate and ocean basins to open and close.

3. Nowadays various scientific theories explain earthquakes, volcanic eruptions and geologic events.